Solids Liquids and Gases

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Cations and Anions

A positive ion is called a cation.

eg.__________

A negative ion is called an anion.
eg ____________

In order to react particles need to collide.

A certain amount of energy is necessary for a reaction to take place. This is called the activation energy.

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Reaction Rates

Four things can speed up the rate of a reaction:

Increasing the surface area.

_____________________________________

Increasing the concentration.

_____________________________________

Increasing the temperature.

______________________________________

Using a catalyst
This lowers the activation energy required.

Chemical and Physical Change

In a chemical change, new substances are formed.

Evidence of a chemical change includes light and heat being given off, and something changing colour (ie becoming a new substance).

A chemical change cannot easily be changed back.

In a physical change, no new substances are made, so they can be more easily changed back.

Oxidation

An oxidation reaction occurs when something reacts with oxygen.


Eg: iron (III) + oxygen --> iron (III) oxide.

Combustion

A combustion reaction is when something burns.
eg. Hydrogen + Oxygen --> ___________

The substance which burns reacts with oxygen in the air (O2).

Most combustion reactions are exothermic (give off heat). Many also give off light.

All combustion reactions are oxidation reactions (but not vice versa).

Reduction

A reduction reaction occurs when something loses oxygen. It is the opposite of an oxidation reaction.

eg.iron oxide + carbon --> iron + carbon dioxide.

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